1) The word "book" contains two vowels: O and O.

2) Usain Bolt of Jamaica holds the world records for the 100 meters and 200 meters sprints, with times of 9.58 seconds and 19.19 seconds, respectively.

3) The Black Lives Matter movement, which gained prominence in 2013, advocates for racial justice and equality, addressing systemic racism and police violence against Black individuals.

4) In Norse mythology, the Valkyries are divine maidens who serve Odin, the chief god. They are responsible for selecting warriors worthy of entering Valhalla and escorting them to the afterlife. They are often depicted as powerful and beautiful figures, riding winged horses and wielding spears.